It is becoming increasingly common for manufactured parts in all industries, and in all phases of development, to be created through an additive manufacturing (“AM”) process. AM processes are technologies that build three-dimensional (“3D”) objects by adding layer-upon-layer of material. Common to AM technologies is the use of a computer, 3D modeling software (such as Computer Aided Design, “CAD”), machine equipment, and layering material. Once a CAD sketch is produced, the AM equipment reads in data from the CAD file and lays downs or adds successive layers of liquid, powder, sheets, or other formats of any suitable material, in a layer-upon-layer fashion to fabricate a 3D object.
The term AM encompasses many technologies including subsets like 3D printing, rapid prototyping (“RP”), direct digital manufacturing (“DDM”), layered manufacturing, and additive fabrication. Examples of AM processes include, but are not limited to, selective laser sintering (“SLS”); fused deposition modeling (“FDM”); stereolithography (“SLA”); laminated object manufacturing (“LOM”); electron beam melting (“EBM”); 3-dimensional printing (“3DP”); the ASTM F2792-12A Additive Manufacturing Process Categories of Binder Jetting, Directed Energy Deposition, Material Extrusion, Material Jetting, Powder Bed Fusion, Sheet Lamination, and Vat Photopolymerization; and other rapid prototyping methods.
However, the convenience and flexibility of AM processes can be offset by structural weaknesses which arise as an artifact of these manufacturing processes. In effect, most AM processes produce a laminated structure which is substantially made from a very large number of thin layers of material. The layers are substantially planar and are relatively strong within this plane (described here as the X-Y plane) because the material is melded or merged together (e.g., via sintering/curing/bonding of a melted/liquid/powder material) relatively rapidly in the X-Y direction. However, each X-Y layer must be at least partially finished before the successive (in the Z-direction) X-Y layer can be built. Accordingly, the material tends to be bonded less strongly in the Z direction than in the X and Y directions.
For these reasons, the weakest direction for AM-produced parts tends to be through the thickness thereof. In addition, bonding between thermoplastic AM parts may also currently be difficult to accomplish robustly due to lack of bonding adhesion between part surfaces.